Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 985c30ef authored by Ralf Baechle's avatar Ralf Baechle
Browse files

[MIPS] Fix aliasing bug in copy_user_highpage, take 2. 



Turns out b868868a  wasn't quite right.
When called for a page that isn't marked dirty it would artificially
create an alias instead of doing the obvious thing and access the page
via KSEG0.

The same issue also exists in copy_to_user_page and copy_from_user_page
which was causing the machine to die under rare circumstances for example
when running ps if the BUG_ON() assertion added by the earlier fix was
getting triggered.

Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 736fad17

arch/mips/mm/init.c

+12 −7
Original line number Diff line number Diff line
@@ -211,7 +211,7 @@ void copy_user_highpage(struct page *to, struct page *from, 
	void *vfrom, *vto;



	vto = kmap_atomic(to, KM_USER1);

	if (cpu_has_dc_aliases && !Page_dcache_dirty(from)) {

	if (cpu_has_dc_aliases && page_mapped(from)) {

		vfrom = kmap_coherent(from, vaddr);

		copy_page(vto, vfrom);

		kunmap_coherent();
@@ -234,12 +234,15 @@ void copy_to_user_page(struct vm_area_struct *vma, 
	struct page *page, unsigned long vaddr, void *dst, const void *src,

	unsigned long len)

{

	if (cpu_has_dc_aliases) {

	if (cpu_has_dc_aliases && page_mapped(page)) {

		void *vto = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);

		memcpy(vto, src, len);

		kunmap_coherent();

	} else

	} else {

		memcpy(dst, src, len);

		if (cpu_has_dc_aliases)

			SetPageDcacheDirty(page);

	}

	if ((vma->vm_flags & VM_EXEC) && !cpu_has_ic_fills_f_dc)

		flush_cache_page(vma, vaddr, page_to_pfn(page));

}
@@ -250,13 +253,15 @@ void copy_from_user_page(struct vm_area_struct *vma, 
	struct page *page, unsigned long vaddr, void *dst, const void *src,

	unsigned long len)

{

	if (cpu_has_dc_aliases) {

		void *vfrom =

			kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);

	if (cpu_has_dc_aliases && page_mapped(page)) {

		void *vfrom = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);

		memcpy(dst, vfrom, len);

		kunmap_coherent();

	} else

	} else {

		memcpy(dst, src, len);

		if (cpu_has_dc_aliases)

			SetPageDcacheDirty(page);

	}

}



EXPORT_SYMBOL(copy_from_user_page);